The invention relates to a vehicle seat with a back rest in which a sliding guide is provided, and with a headrest which is fixed to the back rest by means of at least one guide rod inserted into the sliding guide, and is provided with a functional unit which is connectable electrically with a base unit arranged outside the headrest.
Inter alia in the case of a rear impact, the headrest prevents the head of a vehicle occupant from being thrown rearward relative to the vehicle. In order to be able to develop its restraining effect optimally, the headrest must be adapted suitably to the position of the head of the vehicle occupant with respect to the back rest, in particular vertically. For this purpose, the headrest is arranged displaceably on the back rest by means of usually two guide rods.
Recently, the headrest also increasingly serves to receive various types of functional units such as, for example, a restraint device which is provided with a gas generator and which can provide for an active adjustment of the headrest in the case of an accident, or activates a gas bag which can restrain the head of the vehicle occupant. These functional units, in particular in the case of a unit to be activated in the case of a vehicle accident, must be connected with a particularly high degree of reliability to a base unit, for example an activating device for the gas generator. A particular problem is ensuring the connection of the functional unit with the base unit reliably over the entire possible adjustment range of the headrest with the possible extreme conditions which can occur, namely on the one hand with a headrest which is adjusted extremely frequently in the course of its lifespan, and on the other hand with a headrest which always remains in one position, once selected, in the course of its lifespan.
The necessary reliable connection is ensured according to the invention in a vehicle seat of the type initially mentioned in that the guide rod is used for the electrical connection of the functional unit. In contrast to the hitherto intended solutions, in which the functional unit is controlled or activated remotely, i.e. without direct electrical connection to the base unit, the use of the guide rod allows to achieve a connection of the functional unit with the base unit which is very reliable in operation. The electrical connection, however, can not only serve to control a gas generator but also to control other units accommodated in the headrest, e.g. loudspeakers of a mobile radiotelephone.
According to a preferred embodiment of the invention, provision is made that the guide rod serves as a guide for a cable by which the functional unit is connected to the base unit. In this way, a connection between the functional unit and the base unit can be achieved which is very secure with respect to mechanical influences.
Preferably, the guide rod is arranged adjustably on the back rest.
According to the preferred embodiment, provision is further made that in the lower end of the guide rod, pushed into the back rest, a plug connection element is arranged which engages into a complementary plug connection element in the back rest. The use of a plug connection makes it possible to connect the functional unit with the base unit almost automatically on insertion of the back rest into the sliding guide, or to separate it from the base unit on removal of the headrest, when the two plug connection elements of the plug connection are suitably arranged. In addition, the headrest can also be completely separated from the seat without extra expenditure.
According to the preferred embodiment, provision is further made that the plug connection element arranged in the guide rod is stationary relative thereto and that the plug connection element arranged in the back rest is displaceable relative to the sliding guide. In this construction, the plug connection element arranged in the back rest follows the movements of the plug connection element arranged in the guide rod and hence at the headrest, so that the possibility of adjustment for the headrest is in no way impaired.
According to this preferred embodiment, provision is further made that the plug connection element arranged in the back rest is biased towards the upper end of the back rest by a spring. The plug connection element arranged in the back rest is therefore always biased towards the plug connection element arranged in the guide rod, so that an unintentional loosening of the plug connection is prevented.
According to this preferred embodiment of the invention, provision is further made that the spring acts on the plug connection element arranged in the back rest with a force which is greater than the force which is necessary for the engagement of the two plug connection elements with each other. In this way, it is ensured that on mounting the headrest to the back rest, the two plug connection elements are reliably connected with each other by means of the force which is necessary for overcoming the spring and for pressing down the plug connection element arranged in the back rest by the plug connection element arranged in the guide rod. Furthermore, of course the displaceable plug connection element can also be arranged in the guide rod and the stationary plug connection element in the sliding guide. In addition, it is possible to provide a device which permits pushing the guide rod further into the sliding guide only after closing of the plug connection. Thereby, it is to be prevented that the guide rod is introduced deep into the sliding guide although the plug connection has not materialized.
Advantageous embodiments of the invention will become apparent from the sub-claims.